Group 1 alkali metals

• Alkali metals


  Group 1 elements which are a bit different from most other metals
• Alkali metals


  • Relatively soft
  • Low densities
  • Low melting points
  • Much more reactive than other metals
  • React vigorously with water, oxygen and group 7 elements
• As you go down the group

  • The elements become even more reactive
  • The melting points and boiling points decrease
• Common table salt (sodium) doesn't suddenly catch fire when sprinkled on potatoes, unlike cesium
• Reactivity


  How easily atoms can lose or gain electrons and react with other atoms
• Ionic compounds


  Formed when a metal atom like sodium donates an electron to a non-metal like chlorine, creating oppositely charged ions that are attracted by electrostatic forces
• Ionic compounds formed by alkali metals are generally white solids that dissolve in water to form colourless solutions
• Reaction of alkali metals with water

  1. Alkali metal + water → Metal hydroxide + Hydrogen gas

  2. The reactions become more vigorous going down the group, with the hydrogen gas igniting
• Reaction of alkali metals with chlorine

  1. Alkali metal + Chlorine → Metal chloride salt

  2. The reactions become more vigorous going down the group
• Reaction of alkali metals with oxygen

  Lithium + Oxygen → Lithium oxide

  Sodium + Oxygen → Sodium oxide or Sodium peroxide

  Potassium + Oxygen → Potassium peroxide or Potassium superoxide
• You don't need to know why the particular oxide compounds form, just memorize them
• The reactivity series is the relative ability of elements to displace other elements from their compounds.
• In general, as we go down the periodic table, atoms get bigger and have lower ionisation energies so they are less reactive
• Alkali metals are very reactive because they lose an electron easily due to having low ionisation energy